Effect of Benzyladenine on Transpiration, Water Potential and its Components in Genotypes of Wheat Contrasting in Drought Tolerance

Drought tolerant and susceptible cultivars of wheat, C-306 and Kalyan sona, growing under non-stressed and water-stressed conditions, were sprayed with benzyladenine (BA) at 70 days after sowing (DAS). Observations recorded at 5, 10, 15, 20 and 25 days after spraying revealed that BA increased the rate of transpiration (TR) in C-306 under non-stressed conditions. However, under water stress, the increase was significant only after 5 days of BA spraying. In Kalyan sona BA treatment either decreased TR or did not exhibit significant increase under non-stressed conditions, but caused significant increase in TR under water stress. The increase in TR was elicited through enhanced stomatal opening. Water potential, osmotic potential and pressure potential of both genotypes decreased on account of water stress. The effect of BA was not perceptible on restoration of leaf water potential (LWP) or its components. The effect of BA was possibly confined to stomatal behaviour and transpiration.     

牛腿山羊对炎热气候的适应性的研究

牛腿山羊为个体大，肉用性能好的山地品种，研究牛腿山羊对炎热气候的适应性，目的在于为同类地区引起该品种提供依据，本试验于１９９５年７月２８日至８月１日在新乡县朝阳种羊场进行，随机选取健康，空怀，经产的成年牛腿山羊和本地槐山羊各１２只，采集血样，实验室内测定Ｔ４和Ｋ＾＋含量，选其中各６只，连续３日测定６：００－７：００时和１５：００－１６：００时的毛丛温度，直肠温度，呼吸率和心率，并且同时测定羊舍内白     

Chilling Tolerance and Physiological Parameters as Influenced by Grafting in Watermelon Seedlings

The influences of different rootstocks on chilling tolerance and physiological parameters in wa-termelon seedlings have been studied. The results showed that grafting improved the chilling tolerance. Com-pared with own-rooted watermelon seedlings, the grafted watermelon seedlings had lower chilling injury index,lower electrolytic leakage (%), lower malondialdehyde (MDA) content, higher chlorophyll and proline con-tent, and higher activities of superoxide dismutase (SOD), ascorbate peroxidase (AsA-POD) and de-hydroascorbate reductase (DR) in the leaves under iow temperature stress. There was a considerable differenceof chilling tolerance among different grafted watermelon seedlings due to the difference of rootstock chillingtolerance. After low temperature treatment, the grafted seedling with higher chilling tolerance had lower elec-trolytic leakage ( %), lower MDA content, higher proline content and higher activities of SOD, AsA-POD andDR in the leaves compared with the grafted seedling with weaker chilling tolerance. From these, we could con-clude that chilling tolerance of watermelon seedlings may be related to higher antioxidative ability and mem-brane stability in the plants. The chilling tolerance of grafted seedling could be properly evaluated by compre-hensive physiological indexes but not a single physiological index.     

霸王树的抗盐性研究

鉴于在干旱区农业中利用盐水资源的需求,我们对霸王树在水培生长中的抗盐性进行了研究。NaCl浓度范围为5(对照)至200molm~(-3)。结果表明,叶状枝的生长对盐敏感,在盐浓度为50molm~(-3)时,生长量为对照的60%。根茎比仅在浓度为200molm~(-3)时才显著降低。对其它不同指标也进行了研究,例如水分含量、Na、K及Cl含量、渗透压和CO_2吸收等。这些指标中,叶状枝水分含量和CO_2吸收的降低均与叶状枝生长降低相联系。含盐量增高使叶状枝渗透压增加,这同组织脱水有关。我们认为霸王树在盐水胁迫下不产生渗透压的调节作用。     

离心机主轴形位公差选择标注及检测

介绍了碟式离心机的结构,分析了其传递动力和转动的零件—主轴的功用,选择标注了主轴的形位公差值并提出了单件生产中各项形位误差的现场检测方法。     

Grain Yield and Drought Resistance Indices of Oat Cultivars in Field Rain Shelter and Laboratory Experiments

Oat cultivars (n = 22) varying in origin were examined in laboratory and field tests at Svalöv and Ultuna, Sweden, in 1985 and 1986. Comparisons were made between drought resistance characteristics of juvenile plants and drought responses in yield of crops grown in field. By using automatic, movable rain shelters in combination with drip irrigation systems, both high and low irrigation regimes could be effected in the field experiments.
Black oat cultivars were more stable under water deficiency conditions, particularly on sandy soil. They possessed the highest drought resistance indices both in the laboratory and field. Modern white oat cultivars were found to be most drought sensitive.
Drought resistance index (DRI) and seminal root length (RL), as assessed in seedling stage, were strongly correlated with field drought susceptibility index (S). It is suggested that DRI and RL could be used as selection criteria to increase drought resistance of oats.     

绿豆幼苗期耐盐性研究

绿豆在盐碱地栽培中受盐害最为严重的时期是幼苗期。以２０个绿豆品种为材料，分析了不同ＮａＣｌ浓度胁迫条件对绿豆幼苗期生长的影响。结果表明，不同ＮａＣｌ浓度胁迫条件对绿豆幼苗生长的抑制作用存在极显著差异；不同绿豆基因型对ＮａＣｌ胁迫条件的耐性也存在极显著的差异：绿豆品种在不同ＮａＣｌ浓度胁迫条件下，其幼苗生长量的变化规律呈多种类型，其中遵循直线回归方程下降变化的品种约占半数，遵循指数曲线方程和Ｓ型曲线方程下降变化的品种约占半数。     

Variation in Salinity Tolerance in Sunflower (Helianthus annum L.)

Forty-five accessions of sunflower collected from different countries were screened for salinity tolerance after 2 weeks growth in sand culture salinized with 150 meq l^?1 of NaCl₂+ CaCl₂ (1:1 ratio equivalent wt. basis) in half strength Hoagland's nutrient solution. The results for plant biomass of 45 accessions show that there was considerable variation in salinity tolerance. In a further greenhouse experiment, the salinity tolerance of three tolerant (HO-1, Predovik, Euroflor) and two sensitive (SMH-24, 9UO-985) lines (selected on the basis of their performance in the seedling experiment) was assessed at the adult stage to evaluate the consistency of salinity tolerance at different growth stages. All three salt tolerant accessions produced significantly greater plant biomass, seed yield and seed oil content than the salt sensitive accessions. The tolerant accessions accumulated less Cl^? and more K⁺ in the leaves under saline conditions compared with the salt sensitive accessions. The salt tolerant accessions also maintained relatively high leaf K:Na ratio and K⁺ versus Na⁺ selectivity. Although statistically nonsignificant, all three tolerant accessions had greater soluble carbohydrates, soluble proteins, total free amino acids and proline in the leaves than the sensitive accessions. A field trial conducted in a salt-affected field confirmed the greenhouse results of the selected accessions. This study shows that salinity tolerance of sunflower does not vary with stage of plant cycle, so selection for increased salt tolerance can be carried out at the initial growth stage. Secondly, it is found that there is great variation of salt tolerance in sunflower. Low uptake of Cl^?, high uptake of K⁺, and maintenance of high K:Na ratios and K⁺ versus Na⁺ selectivity in the leaves and possibly the accumulation of organic osmotica such as soluble carbohydrates, soluble proteins, proline and free amino acids seem to be the important components of salt tolerance in sunflower.     

碱茅耐盐性的研究

对碱茅不同生育期的耐盐性试验表明：碱茅成株的耐盐性强，种子和苗期的耐盐性低。种子对硫酸盐土混合盐、碳酸钠单盐和氯化钠单盐室内萌发的耐盐度分别是（溶液浓度）３．４７％、１．０８％、１．５８％。种子出苗期适宜的土壤盐渍度为１．７１２％，临界盐渍度为３．１０％。苗期以后耐盐性逐渐提高，可在２．４７～２．７９％的土壤盐渍度下生长发育正常。成株的耐盐度高达４．２４８％。田间播种碱茅草在０～１０ｃｍ土壤含盐量１．６５％以下时，可以正常出苗。盐分达到１．８５％时，需要加大实际播量，以便全苗。